This Cookbook gives a step-by-step guide to operation of the DBSP
(double spectrograph) at the Palomar 200-inch Telescope. For a
description of the instrument and information needed for advance
planning of an observing run, go to the Overview.
The hardware setup will be done by the day crew. The support astronomer
will help with instrument checkout. The telescope operator will help with setting up the guider and
slitview camera, for which there is separate documentation (see Palomar Autoguider). Many parts of this cookbook
were taken from Marco Bonati's DBSP software user manual.
Despite its intended real-time usefulness, the Cookbook contains
nuggets of instrument theory here and there that might require some
time to digest—so of course a thorough reading in advance of the
observing run is recommended to avoid unpleasant surprises at the
Get to the 200-inch no later than
2:00 pm on the afternoon of your first night to make contact with
the support engineer. The support
engineer is usually on shift from noon to 10pm, and can normally be
found in the office adjoining the 200-inch control room.
Check the white board in the
control room to see if the DBSP has been filled with liquid
nitrogen. The dewars are topped off every 10-12 hours. The night
assistant and Palomar day crew are responsible for filling the
dewars, and logging fill times on the white board. Dewar status may
be seen by reading its temperature from the temperature GUIs
described below. The temperatures are typically 130K for the red
camera, and 163K for the blue camera.
Check with the staff that the
correct dichroic has been installed (changes require taking
instrument off telescope, and are done only in the daytime). Your
green sheet information is in a logbook located on or near the DBSP
control computer desk.
Check that the correct gratings are installed by asking the day
Check that the grating tilts have
been set by asking the day crew. The day crew should have set them
to the values requested on the green sheet you turned in prior to
Check that the
neutral-density-filter knob is set to 0 (it's at top center of
instrument in Cass cage, almost level with base of forks holding the
spectrograph, and has settings 0,1,2,3)—else an ND filter will be
inserted in front of the arc lamp (but not in the sky light path).
Check that the "dust covers"
are open (thin, black-anodized metal covers near the top of DBSP
that can be rotated by hand)—the day crew can show you where these
Decide on a filter from the following table (most observers
do not use filters):
in spectrograph; [b] antireflection coated;
[c] liquid filters are not to be used.
All DBSP turret functions
are controlled by the LabVIEW-based Turret GUI. The Main GUI shows the current filter wheel location for each light path.
Decide on a slit from the following table:
Slit Wheel (128″ slits)
The slits are controlled with the Turret GUI
(see below). The Main GUI gives the current slit location.
See the section on the Main GUI.
In this picture, one can see the VNC control window that has the
DBSP Main and Turret GUIs.
The Blue camera Main GUI is on the left. The Red camera Main GUI is on the right.
The Turret GUI is in the middle.
When you get to the 200-inch control room, DBSP and its computer
workstation should already be set up. Usually a VNC window will be
open on a control room workstation linked to the DBSP computer on the
Mezzanine level. You should see two Main GUI windows on the VNC:
for the red camera, and one for the blue camera. You will operate the
cameras using these two windows. Below is an image of the blue side
Main GUI. The Main GUIs are identical except that the colors are
different (red & blue).
The main window allows you to have general control of the camera. It has
a status area on the top part, and a control area on the bottom part
(the background color is slightly different for the status and
control area). The description below applies to both sides except as
mentioned above, the sync... button, which is BLUE side only.
Note that the sync function does not work at this time.
Status, the upper (light blue) area
detstatus LEDs: There is one LED per detector status:
idle, paused, exposing and reading.
This indicates what is the
current status of the detector.
Links and Error LEDs: command, async: These 2 green
LEDs indicate if the client is fully connected to the Server. Both
LEDs should be green for having full-connection and functionality.
error LED: this red LED will turn on when there is any status
condition (such as a command that was not received, an erroneous
String status controls and progress bars immediate
response: This status shows the response from the server to ANY
requested action (EXPOSE, changing image parameter, etc). It will
normally be a DONE or ERROR <message>.
If there was an
error, the red error LED (2) will turn on, and the color of the error
message will also turn red on the control itself. async:
this will show any message that gets to the GUI asynchronously (not
necessarily related to a previously sent command). This messages can
be just information (like filter changed, or image
expose done), or reporting a problem (like TCS
connection lost, or CCD temperature too high, etc).
aperture: shows the current aperture (in arcsec), read
asynchronously from the instrument when it changes. Be patient, this
status box takes a few seconds to update. filter: shows the
current filter position (filter name), read asynchronously from the
instrument when it changes. Be patient, this status box takes a few
seconds to update. image name: shows the name of the image
that will be (if exposing) , is (if writing), or was (if idle)
written to disk.
Progress bars: read: this green bar shows the read
progress of the current image (in percentage). write: this
green bar shows the write progress of the current image (it is
normally written to disk as the image gets read). This will not move
if the image will not be written. seq: this orange bar
shows the progress of the overall sequence. It will get to 100% only
when all the images of the sequence are done (which means that the
system is idle again).
exp: This yellow, thick bar shows the exposure
progress. It can be seen (considering the system is linear) as a
"counts" progress. This shows the progress in seconds
rather than percentage (elapsed time). The upper limit will expand to
reflect the requested exposure time, so it will get full when the
requested exposure time is done, whatever that requested time was.
Control, the bottom (dark blue) area
All the controls can be changed while exposing. Right after the
exposure is done, and the readout begins, the current control values
are grabbed, so the final image will get those fields (like basename,
directory, type, etc).
Image settings: images path: this is the
directory where the images will be written. object: this is
the object name. This will appear on the OBJECT field of the fits
headers. observer: name of the observer (it will appear on
the OBSERVER field of the fits headers) exptime: the
requested exposure time, in seconds (OEXPTIME of the image headers:
Original Exposure time). number of images: how many images to
take (sequence). write to disk: if checked, it will write the
images to disk. If unchecked, it will just read and display, but not
save to disk. obs.type: observation type. This will appear on
the IMGTYPE field of the image headers. If dark is
selected, it will NOT open the shutter when the exposure starts.
basename: basename for the image. The image name is composed
by the basename and the image number as basename<number> (see
image number control). image number: it will create, together
with the basename, the final name of the image, using this rule:
basename%4d the numeric field will always have 4 places, so it will
fill with zeros to the left. For example, if the basename is bias
and the image number is 4, the final image written will be called
bias0004. use type as basename: if checked, it
will change the basename to match the image type. For example, if
object is selected as image type, it will automatically
change the basename to object also.
Exposure commands/actions GO EXPOSE: it will
initiate the exposure. The "exposure" implies opening the
shutter, exposing by the seconds stated on the exposure time control,
close the shutter, and read/write the image with the specified name
(basename, image number) at the specified directory (image path); all
this as many times as the number of images control states. PAUSE
: This control has meaning only when exposing. If pulsed, it will
close the shutter and wait doing nothing. When the button is pulsed
again (resume) it will open the shutter and continue the exposure at
the stopped count. stop after curr. img: This has meaning
only if there is a sequence (more than 1 image) in progress. In that
case, it will finish the current image (finish the requested exposure
and read/write) and then it will come back to idle (stopping the
sequence). stop now: This has meaning only while exposing. It
will stop exposing immediately (closing the shutter) and read/write
right now. Then it will go back to idle (so it will stop any ongoing
sequence also). If this is done, the image headers will report the
actual exposure time done on the EXPTIME keyword (so
OEXPTIME has the
originally requested value, and EXPTIME has the real one. If not
stopped, those two values will be coincident).
Auxiliary GUIs buttons and quit/abort: abort...:
this very small, square button is located almost on the bottom-righ
side of the image (above stop now) is really hiding two "dangerous"
buttons. When pressed, two new buttons will appear: ABORT and QUIT.
ABORT: this will cause to abort any ongoing activity and
will NOT SAVE ANY DATA. It will just stop. The RED side can be
aborted regardless of what is going on (exposing or reading), but the BLUE
side can only be aborted while exposing—so in the BLUE side the
button will be disabled while reading (no aborts are accepted).
QUIT: this will cause to quit the GUI and shutdown the
correspondent server. This should not be done unless really
The rest of the buttons (binning & ROI, headers,
display, temp, Lamps, sync) will open
auxiliary windows for
different settings as follows in section Auxiliary GUIs.
The Turret GUI is very easy and intuitive to use. It completely
replaces the old blue DBSP control box. At the top are the arc lamp
controls. Simply click on the lamp you wish to use. When a lamp is on,
the lamp button turns bright green. You may have as many lamps on as
you want. The Deuterium and Fe-Ar lamps will turn orange while warming
up and then turn bright green when lit. Please remember to click off
the arclamps when they are not needed. They have limited lifetimes and
are not trivial to replace.
Below the lamps are the four pull down menus that control the aperture, the
red side filters, the blue side filters, and the Turret optical path. To make
a change simply pull down a menu with the mouse and select by putting the mouse
over the menu item and letting go. The aperture and filter selections are listed above.
The Turret choices require a little more explanation. The actual Turret is a disk that
moves mirrors around above DBSP. The purpose of the Turret is to give the observer a way
to change the optical path so that they can view the science target (aperture), the arclamps
(lamps), a wider target field (sky), and nothing (closed).
By selecting "aperture," the observer will be observing the slit in the
slitview camera. By selecting "arclamps," the observer will be sending calibration light
down the DBSP slit. Selecting "sky" will give a wider field of view to
slitview camera. This option might be useful for TOO obsevations, or
to help identify the
proper field when the aperture field is too small. The closed position is never used.
If for some reason the Turret GUI freezes or locks up, click the red QUIT
button at the bottom of the GUI. To restart the Turret GUI, double
click the "launch_auxmon_GUI" icon on the desktop and the Turret should come back up.
Ask the support astronomer or telescope operator for help if there is strange Turret GUI behavior.
This window allows you to select any single Region of Interest
(ROI) on the chip and/or change the x and/or y binning factor. As in
the Main GUI, it has light blue on the status area, and dark blue on
the control area.
The upper part shows the geometry of the array, where Pres:
prescan pixels. Data: Data area of the CCD. Overs: overscan
pixels. amps: total amplifier on the X or Y direction. Total
Size: shows the total size that the image would have if using
full size, calculated as (Pres + Data + Overs) * amps, in the X
direction. (Data) * amps in Y direction (no prescan or overscan area
is used on Y).
Readmode: The upper left yellow is actually a control. It
shows the currently selected read mode, and by clicking on it the
mode can be changed. The BLUE side supports left (shown on the image), right, or
lowerboth (right and left) amplifiers. The RED side only supports
Shows the current status of the geometry, and allows (bottom part)
to change it. Note that Prescan and Overscan size cannot be
changed from the GUI, and that's why on the bottom area
the Total Size stated for both columns (X) and rows (Y)
corresponds only to the Data area. Read Time: Shows the total
read time for the currently selected geometry. The calculation
includes ROI, binning and readmode. show: If selected it will
show, on the correspondent Real Time Display the ROI selected, as a
blue (BLUE side) or red (RED side) thick line. This is just a quick
guidance to the area that has been chosen.
ROISTARTCOLS and ROWS:
starting pixel in x and y
coordinates. The lower left corner corresponds to pixel (1,1).
LENGHTCOLS and ROWS: total size on X and Y. The image area of
the ROI will be then: [Xstart, Ystart: (Xstart+Xlen), (Ystart+Ylen)].
OK: go select the chosen area. full: selects the whole
CCD as ROI (full frame). This is equivalent to enter manually the
full frame values.
The system can be set to start with a pre-selected ROI. For
handling this, there are two buttons: set def: Use the
currently selected ROI as the default, starting value. If this is
done, the next time the system starts it will start with this ROI as
a pre-selected value, and the next time the get default button is
used it will restore to these values. get def: if a change
was made, this button will restore the pre-selected default value.
BIN FACTOR: Changes the binning factor on X and Y. OK:
go change the binning.
The BLUE side has arbitrary binning factors for every
direction (X and Y).
The RED side has only some allowed combinations (X, Y):
(1,1) , (1,2) , (1,3) , (2,1), (2,2), (2,3) , (3,1), (3,2).
display: enables or disables the Real Time Display. If
enabled, it will display the image while it is being read (in "Real
Time"). If it is disabled, the image will not be displayed
automatically. The rest of the buttons will be disabled only if
display is enabled. autoscale: If enabled, the RTD will select
automatically the upper and lower values to be mapped. If disabled,
the user can enter the desired values (z1 as the lower, z2 as the
upper) for the display mapping. z1, z2: the user-selected
values for the mapping. These fields will be enabled only if
autoscale is disabled. scaling type: type of scaling desired.
It can be: unitary, logarithmic or linear (usual). current:
these are status only. They will show the current z1 and z2 being
used for the mapping. If autoscale is enabled, they will show the
values auto-selected on the display, if autoscale is disabled, they
will show the use-selected values on the z1 and z2 controls. For
first time users don't worry too much about manipulating the Real
time Display, it's pretty much stand alone.
This window allows the users to
add/delete/edit any "custom" keyword for the image FITS
The table shows the current custom
keywords. Any of those can be changed or deleted, or new ones can be
added. If the user selects a line with the mouse, it will
automatically fill the fields on the controls (see below) with that
values. This values can be entered manually also.
Below the table there are 3 string
fields, and 1 Type control. KEYWORD: the name of the desired
keyword. Value: the value for the desired keyword. If the type
is not specified, it will assume type string. Type: here the
type can be selected. STR: String. U8: unsigned 8 bits.
I8: signed 8 bits. U16: unsigned 16 bits. I16:
signed 16 bits. U32: unsigned 32 bits. I32: signed
32 bits. FLOAT: 32 bits floating point. Comment: comment
to appear on the comment area of the keyword header.
Then, there are two buttons. Delete:
It will delete the specified KEYWORD. If no keyword with that
name is found, it will have no effect. Apply: apply the
changes. If the specified keyword does already exists, it will modify
it with the new values (specified in the Value and Comment controls).
If the specified keyword does not exists, then it will be added.
After the changes are made, those keywords will become "default",
in the sense that the system will start with those values everytime
afterwards (the changes are actually stored in a header's template
This small window is only for monitoring the detector temperature
purposes. It is generally left on next to the Main GUI so that the
Palomar staff can log dewar temperature with LN2 fills. If it annoys
you, close it.
If the temperature falls outside the allowed limits (usually around
[150,170] Kelvins), the trace will turn red, and the LED will
blink. This serves only as an alarm. If you see this happen, notify
somebody on the Palomar staff. The window updates every 60 seconds,
so if you are restarting the system, you may see blinking lights or
the wrong colors for a minute.
The HIGH and LOW lamps are flatfield lamps that project
from Prime Focus up to a painted square on the dome when the
telescope is pointed to the zenith. The ARC lamp is a mercury line
standard lamp which was installed for the COSMIC spectrographic
multi-aperture mode. COSMIC has no internal calibration lamps. Most
DBSP users use the internal wavelength calibration lamps and not the
dome ARC lamp.
Operation is simple, push the button
with the mouse and the lamp goes on. To turn off a lamp, toggle the
button again with the mouse. The display box below the lamp buttons,
give the "on" status.
NOTE: The RED and BLUE cameras are now running on separate
computers, and the sync function no longer works.
This window is particular to the BLUE side, which acts as a "master"
when the system is run synchronized. For more information on this
please read the general explanation.
This window allows you to synchronize or
un-synchronize both RED and BLUE sides. And to set what the user
wants to be synchronized. The Systems table on the left of the GUI
shows what systems are available. For DBSP there are only two
systems: DBSPBLUE and DBSPRED (for BLUE and RED sides respectively).
On the right side there are the actual controls for this GUI.
synchronize: If enabled, both systems are synchronized. If
disabled, both system are un-synchronized, which means that both
sides can be run as totally independent systems. When the systems are
synchronized, the synchronized LED will turn green, and a check mark
will appear in front of the DBSPRED entry on the table.
The rest of the controls are enabled only if synchronize is
enabled. The fact that the systems are synchronized implies this
Shutter open: shutter will be opened at the same time (BLUE GO
Exposure will be Paused/Resumed/Aborted/Stopped on both sides
(BLUE Pause/Resume, Abort and STOP NOW buttons).
Sequence will be stopped at both sides (BLUE STOP after current
Object and observer will be the same on both sides (specified on
the BLUE object and observer controls)
Besides these basic aspects, there are some other parameters than
can be synchronized if desired. This is the usage of the rest of the
controls on this GUI. add prefix to basename: If checked, it
will add a prefix to the images of both sides (b_ for BLUE side, and
r_ for RED side), so now the final image name will appear as
<prefix><basename><image_number>). directory: If
ON, both images will be written on the directory specified on the
BLUE GUI (image path control). basename: If ON, both images
will have the same basename (BLUE basename control). numbering: synchronized: the image number will be the same for both sides
(BLUE image number control), unsynchronized: numbering is kept
independent for both systems. num of images: If ON, the number
of images of the sequence will be the same for both, set by the BLUE
number of images control. exptime: If ON, the exposure time
for both sides will be the same (BLUE exptime control).
The polarimeter GUI may be found after you start the VNC from the control
room workstation. On the VNC window look for the DBSP folder. Open the
folder by double clicking on the icon. The folder may be hidden by the Blue
camera Main GUI, so look behind it. In the folder you will see an icon
for the polarimeter GUI, double click that icon. The polarimeter GUI is shown
here. The GUI operation is simple. First, press the Init Pol.
initialize the polarimeter. Next, press Cal Home and PA home.
The GUI should
now show 0 for PA angle and HOME for the cal position.
See the table above
for the proper position angles to get
the Stokes parameters you desire. Changing position is easy; simply type in the
angle you want in the Set PA window and hit return. Changing the Cal location
is also easy; type HOME, UV, or IR,
for the three Cal positions. To check
position click on the PA Read and Cal Read buttons.
The Current PA Offset
window should always read 0 at startup.
Taking arc images with DBSP will only show that the beamsplitter is in place. To
test the polarizer calset positions, and the Stokes angles,
you will need to take dome flats. The arc lamps are not in the
polarimeter optical train. If you are unfamiliar with turning on the
highlamp and opening the mirror cover, ask the day crew or the support
astronomer. All calset and PA commands echo position
numbers to the GUI "current" windows, which should tell you that moves have been
made. As a final check, the observer should observe a polarization
standard star to confirm that the correct angles and polarizer
elements are indeed in place. For more polarimeter information see the
Overview section of this web manual.
If directory, basename and numbering are all synchronized, the
system will check automatically add prefix to basename in order to
avoid the images to override each other. In this case the images will
be written as:
BLUE image: <image path>/b_<basename><image_number>
RED image: <image path>/r_<basename><image_number>
If directory and basename are synchronized, but numbering is
unsynchronized, it is the responsibility of the user either to check
adding the prefix, or to keep the numbering distinct enough to avoid
Obtain test frames (to see where spectrum hits the chip &
set your chip readout area on the ROI GUI, see the ROI section).
Perform the following procedure for each camera in use:
Turn on the appropriate toggle
switch on the box labeled COMPARISON LAMPS on the DBSP control box:
He, Ne, Ar are generally good for the red side, hollow cathode
(Fe-Ar) for the blue, Hg or He if you want only a few lines; an
incandescent lamp may be used for flats, but most observers prefer
dome flats. Most lamps take just a few seconds to warm up, but the
hollow cathode (Fe-Ar) lamp takes 20 or 30 seconds. It's OK to leave
lamps on for 10 minutes or so, but not for an hour.
To view these internal lamps,
select SKY with the rotary switch on the control rack sitting on the
guider desk [in SKY mode, the on-axis guide camera directly views
the sky, and the pickoff mirror blocks sky light or outside light
from reaching the spectrograph, but allows viewing of internal
comparison lamps; in SLIT mode, the on-axis guide camera views the
sky in reflection from the polished plates of the slit].
Make a single-camera CCD exposure
by With 1200 l/mm gratings, typical exposures are 1 sec. on the
blue side (more for the Fe-Ar ~20 sec.) and 3 sec. on the red.
Check that bias levels (dark
intensity) are about 5500 counts for the Red camera CCD21, and 3000
for the Blue CCD23.
Move the cursor to the edges of the usable field to be
retained when you trim the display, and write these coordinates down
because they will be inputs to the ROI GUI. Grating changes and
Polarimeter use, moves the spectrum around on the chip. Take some
images, and apply the desired ROI changes, and take some more
images. Remember that the smaller the area read out, the shorter the
NOTE that the following #1,
#2, and #3, should already be done by the Palomar staff. If you have
a concern contact the day crew or support astronomer. Please do not
make any changes without help.
Examine spectra to see that the images of the slit form vertical
lines on the screen. If you find that the blue camera has slit
images turned clockwise, then turn the dewar in its mount
(counter)clockwise to correct; if the red camera slit images are
turned clockwise, turn the dewar (counter)clockwise in its mount.
Note: a quantitative approach is
effective—derive the tangent of the offending angle by the ratio
of x-pixels offset to y-pixel range seen on the display unit, and
match this with a correcting angle whose tangent is the amount of
travel of the dewar-rotating micrometer, divided by the 4-inch
radius at which this micrometer is mounted. Or just take images and
make moves until you get it right.
Check that the center wavelength is on the center pixel or the tolerance you require;
otherwise, tweak the gratings. Don't
forget to use the additional numbers provided by the
grating angle calculator to verify that the spectrum has the correct dispersion, etc.
Calculator caveat: the resolving power returned by the
calculator uses resolution per pixel, not per slitwidth like the
other quantities given (hence this resolving power does not change
with slit choice).
Check the focal adjustment on the
red side; set it as a function of ambient (dome) temperature by
following the instructions taped to the side of the DBSP instrument.
Be careful not to grasp the indicator dial while adjusting, as it is
held by only a set-screw—there is very little backlash in this
adjustment, but it is probably best to approach from the same
direction (lower numbers) each time.
Check the focal settings of the
two collimators: arc-lamp images with a 0.5″ slit should give
~ 3.0 pixel FWHM on the blue side, and ~< 2.7 pixel FWHM on the
red. Also it is important to note that the red camera is a lensed system.
For the low dispersion (158,316) gratings there is significant focus error
associated with wavelength. For example, if you focus in the center of the
158 ln/mm grating, you can expect a focus FWHM in the center of the chip ~1.5
pixels but see 4 or 5 pixels at the extreme red and blue end of the CCD.
The collimators have lots of hysteresis ("backlash"),
perhaps 10 units, so be sure to approach any given setting from the
same direction each time (from lower numbers, by editorial fiat)—
In practice, spectra are fairly insensitive to collimator focus,
and the optimum range is fairly broad. The following table
nonetheless provides a rough guide. If you are alone, focusing
means running up and down the ladder to make adjustments in the Cass
cage. The support astronomer will be happy to adjust the collimator focus
while you take focus images.
Collimator Focus (1 digit = 1905 mm) [a]
Focus for parallel light
Focus for good optical performance
390 – 510
690 – 810
Total focus range
250 – 600
690 – 1070
[a] larger numbers move image plane
further from telescope
Take BIAS frames. In the Main GUI
set the exptime to 0, set the obs. type to bias, set
the basename and comments to whatever you like, and take 10
or so biases.
If you like to take DARK frames,
set the exptime to desired value, set the obs. type to
dark, set the basename and comments to whatever you like,
and take as many as you need.
Take FLATS (flatfielding frames)—either TWILIGHT FLATS on the evening sky or
after the lights are turned out in the dome at 3 or 4 PM. Twilight flats
are a bit tricky to get a decent number of counts, and must be done
just as the sun sets to get the blue side right. Dome flats involve
pointing the telescope to an illuminated spot on the dome, opening
the mirror cover, and exposing. Note that dome flats can have an
emission line around 6708 Å, which, when used in data reduction, can
create a spurious absorption line at 6708 Å in spectra. Flats may also
be done using the internal incandescent lamp (not recommended) and
following the procedures outlined below for obtaining comparison lamp
TAKING DOME FLATS (the popular choice): Please ask for help the
first time you do this.
make sure lights are out in the dome;
have telescope operator or crew
point the telescope at the illuminated patch at the zenith used for
open mirror cover using switch
at telescope operator's console;
open the Lamps GUI, select
HIGH to turn on the
high-intensity dome-flat lamp (select LOW to turn on the
fainter flat-field lamp; select OFF to turn off all lamps);
on the Turret GUI pull down the turret menu and select aperture
allowing light through the slit;
set the exptime, obs. type,
basename and comments, and take an exposure;
take a few short exposures to calculate a desirable number of counts (remember
the shutter is unreliable under 1 second, the red side saturates
~40k, and the blue at ~65k);
to take a series of exposures, enter your value into the number of
remember to select OFF in the Lamps GUI when you're done;
Tell the telescope operator the
desired "ring angle"—the orientation (position angle) of
the slit on the sky, in degrees east of north.
Focus the telescope on a star (you
will need to repeat this once or twice during the early evening as
the temperature changes. The telescope operator will perform this
Make sure the Turret is at aperture
(this allows the center field camera to view the slit and
surrounding field stars reflected from the slit blades, and lets
telescope light into the spectrograph);
Use the hand paddle to adjust
telescope focus until stars in guide camera field appear sharp
(guide camera and DBSP are parfocal); there is a readout of
telescope focus in mm on the RA, DEC display screen; OR there is a
automated focus box on the FLI camera GUI. Ask the telescope operator to
give you a demonstration.
If you are doing spectrophotometry
the telescope operator can call up a suitable source from a
computerized list of spectrophotometric standards compiled by Gunn.
You may wish to do two or more standards during the night,
particularly if accurate flux calibration is important to your
experiment. There is also a standards GUI that can be run for all
Your files are saved to /rdata/DBSP on the DBSP computer.
Sftp file transfer can be easily done from this location.
See the support astronomers for relevant passwords and paths.
There are DVD burners on each of the control room workstations. They
are easy to use "drag and drop" burners. Ask for help the first time
you use them, and take notes. You
are responsible to supply your own media (DVD, -R, -RW, etc.).
Autoguider has comprehensive documentation of its own
Autoguider); we summarize the main points here.
The telescope operator and support astronomer can help you with the finer points and
getting set up. Some observers prefer to have the telescope operator
run the guider. The choice is up to you, but don't hesitate to ask
for help if you get stuck using the guider. BE CAREFUL, the guider
cameras are image intensified, and can be damaged with over-exposure. The main controls that you will use are:
ENABLE button at upper right—turns on the guider;
clicking on it (with left button of mouse) toggles it ON/OFF, and it
changes color accordingly—yellow means it's OFF (i.e. caution,
you're not guiding).
INTENSIFIER GAIN slidebar, 1/3 of the way down on
right side—turn it down (via click-and-drag to left) when slewing,
as you would to protect any camera.
FRAMES PER INTEGRATION and INTEGRATIONS TO AVERAGE
slidebars, about 1/2 way down on right side—the product of these is
the number of (30 Hertz) frames that are averaged in each update of
the display; you might adjust these according to seeing and
brightness of the guide star.
Most of the many other controls may be ignored and left the way
you found them, or the telescope operator advised you to set them. The
on-screen green box within which the guide star position is
calculated (by, eg., a centroid) may be resized by clicking and
dragging on its edges. The crosshairs inside the box display the
current position solutions in x and y; the crosshairs outside the
box disappear when the solution is not found.
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DBSP Cookbook / v 2.1
Last updated: 26 Mar 2016 CMH